The old `Start-FileDownload` was no longer recognized by the pswh
version on my local machine, this updates the OpenCppCoverage install
script to use a still usable cmdlet.
We still want to build VS 2017 through AppVeyor, and those images
have CMake 3.16.2 installed. We could install newer CMake as part
of the build, but since we don't use newer CMake features yet, this
is simpler.
`gmtime*` on Windows fails on dates pre 1970, and because we didn't
check the return code, we would then pass invalid `tm` struct to
`strftime` causing it to assert.
Closes#2944
Turns out that even in GCC, the expression in `__builtin_cosntant_p`
can end up evaluated and side-effects executed. To allow users to
work around this bug, I added a configuration option to disable its
use in internal macros.
Related to #2925
While isatty() is a POSIX interface and theoretically could be used
more broadly than on Linux and macOS, use a conservative approach and
use it on any platform that uses GNU libc.
In case the warning -Werror=conversion is active with GCC, the warnings
about "conversion from A to B may change value" lead to a compilation
error. This explicitly convert the values to address these warnings.
The main reason for this is to be able to distinguish between
different errors (or "errors") based on the return code. Before
this change, it was impossible to use the exit code to figure out
whether a test binary failed because all tests were skipped or
because exactly 4 assertions have failed.
This meant that using `catch_discover_tests` and telling it to
check for exit code == 4 to determine skipped tests could lead to
false negatives.
Most of these will not matter in practice due to C++14 imposing
significant limitations on what else we can make constexpr, and we cannot
have references outliving the constexpr context either way.
